Merge pull request #1 from roylines/express-support

Express support

examples/docker-compose.yml

@@ -0,0 +1,8 @@
+version: '2'
+services:
+  prometheus:
+    image: prom/prometheus
+    volumes:
+      - ./prometheus/prometheus.yml:/etc/prometheus/prometheus.yml 
+    ports:
+      - "9090:9090"

examples/express/express.js

@@ -0,0 +1,17 @@
+const express = require('express');
+const epithemeus = require('../../index.js');
+
+const app = express();
+epithemeus.instrument(app);
+
+app.get('/', function (req, res) {
+  var high = 500, low = 150;
+
+  setTimeout(() => {
+  res.send();
+  }, Math.floor(Math.random() * (high - low) + low));
+});
+
+app.listen(8000, () => {
+  console.log('express listening on 8000'); 
+});

examples/prometheus/prometheus.yml

@@ -0,0 +1,8 @@
+global:
+  scrape_interval:     5s
+  evaluation_interval: 5s
+
+scrape_configs:
+  - job_name: 'express'
+    target_groups:
+      - targets: ['192.168.1.3:8000']

index.js

@@ -1 +1,46 @@
-module.exports = {}
+const client = require('prom-client');
+const metric = {
+  http: {
+    requests: {
+      total: new client.Counter('http_requests_total', 'total number of http requests', ['method', 'path', 'status']),
+      duration: new client.Summary('http_requests_duration', 'request duration', ['method', 'path', 'status'])
+    }
+  }
+}
+
+function ignore(request) {
+  return request.path === '/metrics' || request.path === '/metrics/';
+}
+
+function ms(start) {
+  var diff = process.hrtime(start);
+  return Math.round((diff[0] * 1e9 + diff[1]) / 1000000);
+}
+
+function middleware(request, response, done) {
+  if(ignore(request)) {
+    return done();
+  }
+
+  var start = process.hrtime();
+
+  response.on('finish', function() {
+    metric.http.requests.total.labels(request.method, request.path, response.statusCode).inc();
+    metric.http.requests.duration.labels(request.method, request.path, response.statusCode).observe(ms(start));
+  });
+
+  return done();
+};
+
+function metrics(req, res) {
+  return res.send(client.register.metrics());
+}
+
+function instrument(app) {
+  app.use(middleware);
+  app.get('/metrics', metrics);
+}
+
+module.exports = {
+  instrument: instrument
+}

package.json

@@ -26,7 +26,13 @@
     "node": ">=4.0.0"
   },
   "devDependencies": {
+    "chai": "^3.5.0",
+    "express": "^4.13.4",
     "mocha": "*",
-    "mocha-circleci-reporter": "0.0.1"
+    "mocha-circleci-reporter": "0.0.1",
+    "request": "^2.72.0"
+  },
+  "dependencies": {
+    "prom-client": "^3.4.1"
   }
 }

test/express.js

@@ -0,0 +1,34 @@
+const express = require('express');
+const epithemeus = require('../index');
+const request = require('request');
+const should = require('chai').should();
+
+describe('express', () => {
+  before((done) => {
+    const app = express();
+    epithemeus.instrument(app);
+    app.get('/', (req, res) => {
+      res.send();
+    });
+    this.server = app.listen(3000, done);
+  });
+
+  after((done) => {
+    return this.server.close(done)
+  });
+
+  it('should return 200 for /', (done) => {
+    request('http://localhost:3000/', (e, r, b) => {
+      r.statusCode.should.equal(200); 
+      return done(e);
+    });
+  });
+
+  it('should return 200 for /metrics', (done) => {
+    request('http://localhost:3000/metrics', (e, r, b) => {
+      console.log('BODY', b);
+      r.statusCode.should.equal(200); 
+      return done(e);
+    });
+  });
+});